1. Field of the Invention
The present invention relates to energy dissipating devices which are employed particularly, but not exclusively, in structures impervious to seismic occurrences and more particularly to an energy dissipating device having higher functional and structural features than those of the energy dissipating devices which are presently used.
2. Description of the Prior Art
As known, a structure which is to be impervious to a seismic occurrence must exhibit a high capacity of dissipating energy in the post-elastic field. This capacity of dissipating energy can be particularly assigned to special dissipative devices arranged in suitable locations of the structure. Because such devices dissipate the energy supplied to the structure by a violent earthquake in a controlled manner and according to predetermined forms, they can assure a good seismic protection of the structure by preventing the collapse thereof and by containing the damage to the structure.
As a matter of fact, the main object of these devices is to reduce the response of the whole structural system in the case of very violent earthquakes by suitably controlling the very high stresses transmitted to the supporting structures until an "integral seismic protection" of all the elements forming the primary resistive system has been possibly attained.
The most recent energy dissipating devices employed for this purpose to take advantage of the elasto-plastic behavior of structural metal elements, which are subjected to flexural, normal and torsional stresses, or a combination thereof, are usually affected by the following disadvantages:
the load-deformation diagram beyond the elastic limit is not constant, but variable because a metal element changes its geometry, with resulting increase or decrease of the stiffness; and
the plastic deformations tend to localize in some restricted areas, thereby causing the premature failure of the metal elements after a few cycles of alternating stress.